Post-Exposure Prophylaxis (PEP)

Reviewed by: HU Medical Review Board | Last reviewed: 5/31/22

PEP (post-exposure prophylaxis) is a treatment option given after potential exposure to HIV has occurred. PEP involves taking a combination of antiretroviral medicines called ART. PrEP (pre-exposure prophylaxis) is different from PEP in that PrEP is taken before a potential exposure occurs, and on a long-term basis. For example, PrEP may be taken every day by an individual who is sexually active with a partner who is living with HIV.

How does PEP prevent HIV transmission?

PEP, on the other hand, is designed to be used in emergency situations only, and after a potential exposure has occurred. PEP involves more medications at higher doses than PrEP and cannot be used on a regular basis. If you consistently have a higher risk of getting HIV, PrEP is a more beneficial, long-term option.1-4

Instances when PEP may be appropriate include:

  • After a potential workplace exposure, such as an accidental needle stick when working with an individual living with HIV
  • After a sexual assault, especially when the HIV status of the assailant is unknown
  • After a sexual encounter with an HIV-positive individual (or potentially HIV-positive individual) in which the condom or other methods of barrier protection failed or broke
  • After sharing needles or works (things used to prepare drugs) for injection drug use with an HIV-positive individual (or a potentially HIV-positive individual)

PEP may be considered after any event that could lead to the potential transmission of HIV. PEP can greatly reduce the chances of getting HIV after a potential exposure if it is taken exactly as prescribed, however, it is not 100 percent guaranteed to prevent the transmission of the virus.4,5

How soon should I start PEP after a potential exposure?

Contact a healthcare provider or seek medical attention as soon as you think you may have been exposed to HIV. PEP needs to be started within three days (72 hours) of the exposure; the sooner the medication is started, the better it is at protecting you. PEP works the most effectively if it can be started within 24 hours of exposure, if possible.

If you think you may have been exposed to HIV at work, talk to your supervisor immediately. There are often resources available and protocols in place, especially in healthcare settings, for potential exposures to HIV and other infectious agents.4,5

How do I take PEP and what are the side effects?

PEP is taken one to two times a day, for 28 days. Your healthcare provider will tell you how often you should be taking PEP. It is important follow your providers instructions as carefully and consistently as possible. Tell your doctor or healthcare provider if you are taking any other medications, as some medications may interact with PEP. Some individuals may experience nausea when taking PEP. Alert your provider if you experience any side effects that are bothersome or may prevent you from taking the medication as directed.4,5HIV testing will often be done when an individual presents for PEP (to ensure the individual wasn’t already HIV-positive prior to the exposure) and will be completed again about 4-6 weeks after the exposure. Repeat testing will often be completed around three to six months after the exposure, to ensure that HIV transmission did not occur.6

Medication regimens for PEP

The medications used in a PEP treatment regimen may vary based on an individual’s age or other medical conditions. Regardless of the exact medications used, PEP is usually taken for 28 days. Various combinations of HIV medications used as PEP exist and will depend on an individual’s specific situation. Your doctor or healthcare provider will let you know what medications are recommended in your specific situation.

Paying for PEP

Some insurance providers will cover PEP. However, if you do not have insurance or your insurer does not provide coverage, there are other options. There are medication assistance programs created by the manufacturers of PEP medications that may be able to provide reduced or no-cost treatment. Alert your healthcare provider if you think you will have difficulty affording PEP, and they will work with you and the medication manufacturers to come up with a solution.

If you were exposed to HIV at work, your workplace may have insurance or workers’ compensation that covers your PEP. Talk with your supervisor or a human resources (HR) representative at your work for more information.

If you are a victim of sexual assault, you may be eligible for financial support through the US Department of Justice’s Office for Victims of Crime.4

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